1. Field of the Invention
The present invention relates to an apparatus and method for performing a power scanning in a mobile communication terminal having a dual Subscriber Identification Module (SIM) card. More particularly, the present invention relates to an apparatus and method for providing a power scanning that enhancing power performance and time by utilizing two Radio Frequency (RF) chips for managing respective SIM cards of a dual SIM card in a mobile communication terminal.
2. Description of the Related Art
Dual Subscriber Identification Module (SIM) phones have been developed to allow users to manage and use two phone numbers via one mobile terminal in a Global System for Mobile Communications (GSM)/General Packet Radio Service (GPRS)/Enhanced Data Rates for Global Evolution (EDGE) mobile phones. By utilizing a dual SIM phone with two SIM cards, the performance can be improved when compared to the conventional single SIM phone.
In operation, the above terminal performs the power scanning for each band supported by the terminal when power is on. That is, the terminal scans signals of neighbor cells for each band supported by the terminal. By using a power scanning result, the terminal can select a cell capable of receiving a service with best quality.
FIG. 1 illustrates a conventional method of power scanning in a mobile communication terminal with a dual SIM card.
Referring to FIG. 1, a terminal 100 with two SIM cards includes two Radio Frequency (RF) chips 101 and 102 for managing the respective SIM cards. Respective Radio Resource (RR) layers of the two RF chips 101 and 102 transmit power scanning request messages to corresponding Layer 1 (L1) layers. The respective L1 layers of the two RF chips 101 and 102 perform power scanning on a full band (e.g., 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz) supported by the RF chips 101 and 102, gather a power scanning result according to the receive signal strength level, and transmit the scanning result to corresponding RR layers using a power scanning indication message. Accordingly, the respective RR layers of the two RF chips 101 and 102 can utilize the power scanning result during a cell selection process.
The above power scanning process must be performed in order for the terminal to acquire a normal service. However, the power scanning mode consumes the most power among all processes of the terminal, and in case of a quad-band phone supporting up to four bands, a longer time is required for the process. In case of the dual SIM phone, the power required to transmit a power scanning request message by the respective RR layers of the two RF chips to corresponding L1 layers is as twice as that of a single SIM phone. In addition, in case of the dual SIM phone, the time required to perform the power scanning is equal to that of the single SIM phone only if it is assumed that the two RF chips perform simultaneously during the power scanning.